Mullvad VPN
No registration
Crypto-friendly
Mullvad is a VPN service that helps keep your online activity, identity, and location private. Only €5/month - accepting Bitcoin, cash, PayPal, and more. Mullvad does not require account registration or any personal information (name, address, etc).
Notes:
Mullvad's VPN clients have been audited by Cure53 and Assured AB in a pentest report published at cure53.de. The security researchers say that they are happy with the results of the audit and the software leaves an overall positive impression.
iVPN
No registration
Crypto-friendly
IVPN is a VPN service offered by Privatus Limited based in Gibraltar. Privatus Limited has been independently audited by cure53 and has undergone a no-logging audit and a comprehensive pentest report.
Notes:
Like Mullvad, iVPN does not require an email address to generate an account. iVPN also accepts Monero for anonymous payments. Lastly, they have undergone a no-logging audit which concluded in agreement with iVPN's no-logging claim.
ProtonVPN
Registration required
Not crypto-friendly
ProtonVPN is a VPN service operated by the Swiss company Proton AG. ProtonVPN, based in Switzerland, is under the privacy protection of Swiss privacy laws. They accept, PayPal, & more, and have been independently audited.
Notes:
Though Proton is pretty trustworthy, they do not accept cryptocurrency as a payment easily. You can pay them in Bitcoin, which is not anonymous, but you must reach out to them stating that you would like to pay in Bitcoin.